Electrical signaling arrangement



Nov. 16, 1943; R. TAYLOR ET AL 2,334,591

ELECTRlCAL SIGNALING ARRANGEMENT I l Filed March 14, 1942 s Sheets-Sheet 1 sanooas -117/W 1b 2030 40 6'0 6'0 in 8 0 9'0 160 #0 rv/son'w Mzu sEcorvos MAKE Y lNVENTERS REGINALD TAYLOR GEORGE THCMAS BAKER ATTORNEY Nov. 16, 1943. R. TAYLOR ET A1.

ELECTRICAL SIGNALING ARRANGEMENT Filed :March'l4, 1942 3 SheetsSheet 2 REGINALD TAYLOR v GEORGE THOMAS BAKER ATTORNEY Nov, 16, 1943. R. TAYLOR ET AL 2,334,591

ELECTRICAL SIGNALING ARRANGEMENT Filed March 14, 1942 s Sheets-Sheet a INVENTORS REGINALD TAYLOR GEORGE THOMAS BAKER ATTORNEY Patented Nov. 16, 1943 Reginald Taylor and George Thomas Baker, Liverpool, England, assignors, by mesne assignments, to Automatic Electric Laboratories, Ino., Chicago, 111., a corporation of Delaware 1 Application March 14, 1942, Serial No. 434,762 In Great Britain April 28, 1941- 27 Claims. (01. 1795-18) The present invention relates to electrical signaling systems such as automatic telephone systems in which trains of impulses are utilised to cheat the positioning of selective apparatus, and it is more particularly concerned with improved arrangements for responding to control impulses whereby greater reliability. may beobtained when-signaling over lines the characteristics of which cover a wide range. a

The arrangement at present in general use for responding to trains of impulses comprises an impulse responding relay, usually designated A, together with two slow-to-release relays B and C. These latter relays are arranged to be dependent on the break and make periods respectively of relay A in thatv relay B operates as soon as relay A operates and then subsequently remains held due to-its slug during the break pulses of each impulse train, while relay C operates on the first release of relay A via operated contacts of relay Band then remains held due toits slug during the make pulses'of each impulse train. These relays will therefore fall away if the period during which they receive-V no current is greater than the release time determined by the slug. t

In automatic telephone systems, in which the arrangements according to the inventionrhave' their widest field of use, trains ofv impulses are in the majority of casesgenerated bysubscr'ib-.

of each selecting switch must be able to respond satisfactorily to any, combination of, operating conditicnswithin p-re-arranged limits. Eachof the slow relays B and C i dependent both on the rate or speed of the received trains ofiimpulses which is determined by the adjustment of the subscribers impulse senders and alsoonth pulse ratio of the received impulses which is governed chiefly by the line conditions which exercise a distorting efiect on the ratio of the impulses transmitted thereover. g

The operating range of the present Band C relay arrangement can be extended by making the release lag of the relays long enoughto cover the variations in received impulssp'eed and ratio, but this solution to the problem will result in the case of the B relay in the undue-delaying of the release of the selecting switch after the calling subscriber has hung up and in the case;

of the C relay will undulyincreasetheinten' digital pause required. A compromise must be therefore effected and the relays "B and C are accordingly adjusted to'have release times within certain minimum and maximumlimits to enable them to fulfill the diverse functions required of them to the'bestadvantage. The object of the present invention is to provide an impulse re sponding arrangement of improved capabilities in which moreover it is possible to dispense with the critically-adjusted slow relays hitherto employed.

According to one feature of the invention, in an electrical signaling arrangement employingv one or, more trains of impulses for control purposes, an impulse responsive device including a timing device is arranged so, thatwhen' the timing device has-determinedth'atthe,sum of-the periods of which an-impulse ismade up exceeds a predetermined time "interval *regardless ,of the ratio 0f the different periods a; controlswitching operation is effected, such predetermined time interval exceeding an interval; substantially equal to the length era-complete impulse atthe sl0W- est tolerable speed. i 7 I v According to another feature of the invention in an electrical signaling; arrangement having control operations performed in response to "one or more trains of impulses which consist of either interruptions of a closed circuit or closures of an open circuit, the sustained, opening or closing of said circuit eiiecting a further control operation, due to the interval from a given point in one impulse to substantially the same point in the next exceeding ahpredetermined value regardless of the ratio of the open and closed periods, a circuit change is efiected at the-receiving end the nature of which depends .upon whether the control circuit is thenopen or closed. 1

A further feature oiv the invention is thatin an electricalsignaling arrangement having control operations. performed in response to, one or a further control operation, the timing operationwhich serves to initiate the furthercontrol operation is effected by a timing device, whose 'operation is detectable independent of anymovi'ng part. j a

1 According to still another feature of theinvention in an electrical signaling arrangement eln ploying one or moret'rains of impulses for-control purposes, a timing device is set inactionlon the satisfactory operation of the equipmentwhich responds to individual impulses, is restoredto' normal at the commencement of each' impulse,

and serves to effecta switching operation after 10. Fig. 1 shows diagrammaticallytheephone instrument or other form -ofimpulse sender and a selector switchover a transmission' line which may include impulse repeating, a1;-

rangements; Fig. 2 is a form of the'well kn'own graphical target diagram byrmeans ofzwhicnthea performance of impulse responding arrangements 1 both of the present and proposed type m yrbe; compared and analysed; Fig. 3 shows graphically anrimpnlse traimof-two impulses; Fig. 4 shows: a circuit diagram: of; a. lililroutlete group selector switch of theyerticaland rotarytypearranged to haveso-ca-lled' rectangular motion, for instance of:.the mechanical construction disclosed iii-United States. Patent No. 2,028,689, granted Ja'nuaryZl, 1936,: to R. N. S'axby, and Fig. 5 shows a .circuit: :diagram of? a IOU-outlet ilnal selector switch of the. vertical and rotarytype with aseparate release magnet so that the wipers restore to' normal by retracingthe path over which=they have: been set.

Referringnow-to Fig.1, the impulse sending device shown on the left is assumed to be arranged to: deliver impulse traint of- -sim-ple breaks and makes at 'anominal rate of ten impulses persecon-d, each impulse' having. a break-to-make ratio of -2 lfso that the break periodis therefore 66.6 of the whole impulse, and the actual durationis 66.6 milli-seconds. Tolerance-limits of 63% to 70%: are-assumed-tobe' allowed for the break ratio, while the-limits ofimpulse "speed are; from 9-11 impulses per second.

Referring now to-Fig. 2, the-various possible break periods in-milli=secohdsare plotted ver-- tically against make periods horizontally, linear scales beingfadopted-instead, ofthemore usual logarithmie scales for the purpose of simplicity. Eight diagonal lines representative of various dial speeds'from '7 to 1.6 impulses per second'have i been drawn, and their derivation will be appreciatedfrom reference-to the 10 impulses per second line. Here-itwill be seen that for all points thereonthe surno-fthe break-and make periods is IOO-miHi seconds; thenominal dial speed of 10 impulses-per second with a bretk-to-Ihake ratio of 2:1 being represented on the diagramby the point" X. The little. quadrilateral. in. the centre of. the diagram illustrates the previously mentioned impulse sender, limits of 9-11 impulses per secondiand. 63'70% breakratio.

Althoughthe range of impulse sender speeds is limited to 9-1'1'impulses1per second, the exchange, selectingswitches are. designed to workbetween limits offromfldqi: impulses per. second so. as to, give a' further margin of tolerance on the adjustmentofthese pieces ofmechanism andthese in m m-andmaximumlimitsareindicated by ma ing .ti .1e.,7"and liimpmses per, second line do ed;

The 7 ransmission... iineflbetween the. impulse.

sending device andtheselectine. switch provides theimainvimpulse. distorting element, and. ale. thonshithasnocfiect .on impulse. sp ed, it may.

distort the impulse ratio to such an extent that the input to the selector may lie anywhere along .the line respresentative of the impulse speed in question. Hence for the various impulse speeds 7-14 impulses per second, the input to the selector switch may be anywhere within the area bounded by these dottedlines, together with the break and-make axis. If-the selector switch is to allow of the Widest possible variations in transmission line limits within the impulse speed ran e, itshould berespcnsive to as much of this area as possible.

The working area of typical selector switch havingthe present A, B and C impulse responsive relay combination-is bounded on one hand by the 'Tandlimpulses per second lines and on the 'otherhandrby-the curves marked B and C which are respectively characteristic of the limits for the-selector B and C relays. In the region between'the B curve and the break axis the make periods-lareinsufiiciently long to allow the. B relaytficdhold'during the impulse train, While in theregionbetween the C curve and the make axis thepulses delivered to relay C'during the break periods'areinsufiicientlyslong to;allow this relay to holrl during:impulsing. In these two areas therefore, the -selector switch fails to meet possibl'erre'ceived pulses owing to failure of the B or C relay as the casemay be, and'the arrangement according:to:the invention enables some or all ofwboth 'oithese' areas to be brought within-the ranger)! operation of the selector. For thispurpose the individual functions of the Band C- relays are combined into a single impulse{speed measuring circuit adapted to measurethe duration of each complete impulse of a traini the; measurement period extending betweenarparticular point in one impulse and the samepoint-in thesucceeding impulse. Direct measurementis not employed, it being merely determinedwhetherthe actual length of each impulseis greater or less than a fixed predeterminedmeasuredperiodwhich is equal or approximatelyequalto the longest length of impulse which can'be tolerated, namely, a 143 milli-second impulsewhich correspond to the minimum dial speed of seven impulses per second.

Theitimingperiod is preferably arranged to run from the beginning of the break period of the firstimpulse of a train and if a succeeding break is not.rec eived within this period, it is an indication'either. that the impulse train has finished or thatthe subscriber hashung up prematurely andthe selector switch concerned may accordingly'be released: Asthe impulse length is unaffectedby variations in impulse ratio, the arrangement. according toithe invention is dependentonlypnvariations in. speed and since impulse speed is. unaffected by varying line conditlons,..an improvement. inthe o erating range isltobejexpected.

The; improved impulsev responding arrangement according to the invention will be better appreciated from the following description of its application to twodifierent automatic switches ofther typeused in telephone systems where, for tbepurposemi speed timing, use is made of a dischargeable. condenser/resistance timing circuitwhichafiel. apredetermined charging period builds: 119 a suificient, po entialacross the con-.

denseroto strike. a. neon" tube connectedin circuit therewithand;energisc a relay to perform.

theirequired. ontrolling, un tion.

Considerins;. ncW- th ci uit ,qpe atian; of. the

group selector shown in Fig. 4, when the switch is seized,; the loopextended forward from" the subscribers telephone "instrument over the incoming negative'and positive leads operates relay A, whereupon relay B'is operated via resistance YA. This relay on operati g-at armature bl applies a guard earth to the incoming private lead P, at armature b5 lights the supervisory lamp LP, at armature b6 completes a local locking circuit for itself and at armature b8 extends dial tone from common lead ID to thecalling party, the tone finding a balanced circuit to line by induction through the windings of relay'A;

The subscriber nowdials the first digit of the wanted number and relay'A'responds thereto.

On the first release of this relay,a quick discharge circuit is completed for condenser QB via the vertical magnet interrupter contacts om, resting armatures M6 and al and operated armature b5; resistance YA to battery so that this condenser QB, which is used for theimpulse speed timing purposes, will not have any initial charge when it subsequently commences the timing operation. Relay A also at armature a2 completes an operating circuit for the vertical magnet VM via rotary ciT-normal springs NR2, armatures a2, hl, b2 and hr5, an'd test link TL to earth over common lead l4 via delayed release alarm equipment. Magnet VM-on energizing raises the switch shaft and wipers to level I, whereupon the offnormal springs N are mechanically operated, and magnet VM also opens its interrupter contacts om so as to open the discharge'path for condenser QB. When the oif-normalspringsare operated, lcontacts N2 complete acharging' circuit for condenser QB via armature bl and resistance YB to positive battery which isconnected to common lead I5. The values of the condenser and resistance and the positive battery potential are such that if this charging circuit is maintained uninterruptedly for a period of the order of 120 milli-seconds, which added to the vertical magnet operating time oi, say, 20 milli-seconds gives a total period representative of the longest complete impulse which can be tolerated; condenser QB will be charged to' the striking voltage of the neon tube At the end of the first breakperiod, relay A re-operates and opens the energising circuit of the vertical magnet at, armature a2 and at armature al prevents-a discharge circuit, being completed for condenser QB after the interrupter springs om close. Duringv the ensuing make period condenser QB continues to charge.

Assuming that the digit dialled is a or more,

the second break period will commence before condenserQB has time to charge up to the striking voltage of neon tube NT. Hence when relay A releaseson the second breakpa rapid discharge. circuit is completed for condenser QB so as to.

restore thiscondenser to normal, while the magnet VM is energised a second time. Condenser QB again commences to charge on the operation of the vertical magnet interrupter. springs and the cycle of operations described is repeated until the Approximately MOmiIIi-seconds after the commencement of the break period of the last impulse, the voltage across condenser QB rises to the flash point of neon tubeNT, whereupon the tube strikes andbrings up relay H. This relay on operating disconnects anyfurther circuit for last impulse of the train is received.

the vertical magnet at-armature hl and atthe' same armaturecoxnpletes a temporary locking circuit for its right-hand winding and also a selfinterrupteddrivingcircuit-for the 'rotary magnet BM via its interrupter contacts rm. .Magnet RM on energising causes the wipers to cut in on to the first contact of the selected level and also opens its interrupter contacts rm, while the rotary oil-normal springs NR are mechanically operated.

If the first outlet on-the level is busy, the test wiper P will encounter earth or booster battery metering potential, and accordinglywhen the magnet interrupter contacts rm open at the concluslon of the magnet strike, relay H will remain held over its left-hand winding fromthe potential encounteredby the testwiper, the initial operating circuit for relay H having of course been opened at this time by the extinction of the neon tube-NT. Relay H therefore remains operated when magnet RM releases and when contacts rm re-close, relay H is held once again over its right-hand winding and the magnet again energises to move the wipers on to the second outlet. This cycle of operations continues'until a free outlet is encountered or until the wipers are driven to the eleventh position.

If the former operation occurs,- test wiper P fails to pick up potential on -the contact it then engages and accordingly relay H releases quickly when the contacts rm' open, thereupon opening the driving'circuit for the magnet and extend'-.

ing earth forward fromarmatures b3 and b2 over the test wip'er'P to busy the outlet seized. Relay H on releasing also brings up relay HR overresting armature 7L3, rotary oiT-normal contacts NR1 and armature b5 to earth, and'thi's relaylocks over its armature hrl and at its armatures M2," M3 and hr4' switches the negative,

positive and private conductors through to the.

V overarmatures bl and (M4 and then subsequently. remains held from "the holding earth' which is iWhen the parties clear-at the end of the ensuing I conversation, earth is removed from the P conductor at the final selector switch of the train and relay H thereupon releases, thus permitting relay HRto fallaway; A self-interrupted driving circuit for the rotary magnet RM is'the'n completed from the earthed delayed alarm release lead M, link TL, armatures hrS. and'bz, contacts NI and rm, magnet RM to battery. 7 Accordingly the wipers are rotated clear of the banks, after which they ifall andthenj rotate back below the banks under spring tension to.

their normal position ,where the homing circuit is opened at the off-normal springs NI. Preferably the rctary magnet ,is mechanically prevented from opening its interrupter contacts dur step, where the test wiper P fails to encounter any busying potentialand relay H releases as for the free outlet condition, An earth is thereupon extended over armatures b3 and M to operatean: verflow mete connected to the 11th on a t over the lead. It and elayis QIJBI': ated in usual: manner. Ifhe 111th. stepmeeative and: positive outlets are wired: ,baolg into; ther relay circuit; so that. with the Ope t on ofre ay I-IR,'re1ay A will remain held ,over the calling sube scribers loop and thus relays B,,.I-Ia.andIlRalso remain operated. At the 11th step carnjcontacts S2 and S3 busy tone and busy flash batteryere extended over commonileads H and-irrespect ve and thence through thewind ngs of rela A to the callingline sothata busy. indicationgivento the calling party, When he subsequently hangs up, relay A releases and brings down relay Batter a slight interval RelaySHand HR. then release in;turn and, the previously traced circuit for the, rotary magnetis completed-and the switch Wipers are restored as before.

Assuming now that after taking the. selector switch into use thecalling subscriber hanss before dialling, relay A, in releasing wilLproduce the same effect as the first break impulse'of an impulse, train and will energize the vertical magnet VM; while relay B will remain locked to battery via resistance YA; The vertical. magnet on energising raises the wipers to the first level, opens its interrupter contacts cm and brings about the operation of the offenormal springs, so that a charging circuit is completed for condenserQB. After the 12!) .milli-second timing periodhas elapsed, the neon tube NT will flash and operate relay H, whereupon ;the vertical magnet circ'ultwill be disconnected at armature h] and a selfeinterrupted driving circuit forthe rotary magnet RM will be completed at the same armature. The wipers will therefore cutin on thefirst level and the magnet RM will operate in a self-interrupted circuit until; either a free outlet is foundor the 11th stop is reached. Relay. H then releases, since no holding circuit is com: pleted thereto from the test. wiper over its lei-t1 hand winding and relay HR operates, .Since relay A is de-energised, relay HR now completes a circuit at armature hrfi for short-circuiting and releasing relay B and OILthE releaseof this: relay relays H and HR release in turn since no holding earth is fed back from the succeeding switch A self-interrupted driving circuit is then a a n comp or h? rotar m net RM a the switch rotates its wipers clear of the banks a d est hem- 9 h home p t ns as n h case just describedof release on receipt of a busy signal I,

Considering now the operational the Hill-out,-v let final selector switchs'hown in. Fig. 5, inthis circuit the arrangements are such that if relay A is de-energised when thespeed timing device. comes into operationat the end of a timing period, the switch is at once restored to its normal position, Further, since the switch is to respond.

to two digits, the speed timing device on coming i to. perati n a the nd f th j ul train is' arranged, with relay A operated, to change over the impulsing circuit from the vertical to the rotary magnet in readiness for the second impulse train and is arranged at the end of the second train with relay A operated, to initiate testing of the selected outlet. 7

Referring now to the circuit drawing when the switch is seized, relay A operates and brings up relay'B which looks over its armature bl and at armature, b3 applies guarding and holding earth to the incoming Plead. 6n the reception of the first train of impulses,

relay A'responds and on the first release-a discha e. circuit; s 1 om eted; or; conden Q4 via vertic l. and retarrmas e in err n er con: ac sv van rm!- restineannature c! andesis a cer'h. s that t iswndeeser. hichis heed icr'th m u ses eed imin i cuits. l o u sequent mmence mins h any s dua cba ge thereon t he a e t m a erm tur a. an. operating circuit is completed tor-the verticalmas e an thi n ne e sins a s the switc shal and wip r to level I whe eu n the oil-norm s in N e o er te d th nte rupter nteets we re o en to dise r ct he di char e. at iq c nden e QA- nerma con eets il thereu on-com te a cha ins: c rc i e conde er Q4. fr m' a ii ve e t r-" over when lead l2, a ia e. res tane YA; c ntact .32. restin a mature 2 a d tent sts NL. e stance Y be n t o give 3 Wmi period of th 7 o de 120 in -second which added to the vertical magnet operating me c say 2 .1.ni n i s a e l' fie representative-of the longest complete impulse whichcan be tolerated At the end'of the first break period, relay. A re-operates and opens the energising circuit of the vertical magnet at armature a; and at armature a l prevents a clischarge circuit being completed ior condenser QA after the interrupter contacts 12m close, During the ensuing make period condenser QA continues tocharge. 1

If the impulse traincomprisestwo or more impulses, the second break period will commence before condenserQA has time to charge up to the striking voltage of neon tube NT and hence when relay A releases on the second break, a rapid discharge circuit-is completed for condenser QA so as to restore this condenser to normal, while relay B- dependent on relay A sothat the switch will release in a manner later tobe described if relay A is normal at this time. Belay C also at armature c2 completes a temporary lockingcirui r i s f a a a m u e c3 m le s an ene eis ns circu t r h SW r P 'QF? r l On the operation of relay E, the impulsing circuit is changed; over from the vertical magnet v to the rotary magnet RM at armature 64, while a local locking circuit independent of armature a3 is completed for relay E at armature e5. The holding circuit for relay 0' is opened at the same armature and this relay now releases, since condenser-QA will have completed its discharg through neon tube N T by this time, while at armature eZ the charging circuit for condenser QA is opened. Relay C on releasing, at armature cl re-prepares the impulsing circuit and at armature c3 maintains the locking circuit for relay E independently of contacts NR4,

The switch is now ready to receive the second train-of impulses and when thisar-rives, relay A releases on the first break asbefore and there uponenergises the rotary magnet RM and completely-discharges condenser- QA. -Magnet RM contacts of the selected level, andopens its contacts rm to disconnect the discharge circuit for.

condenser QA. The rotary off-normal contacts NR are also mechanically operated and at contacts NR2 complete a new charging circuit for. condenser QA overthe operated armaturecz and contacts NI. Relay Are-operates at the end of the first break period andopens the energising circuit of the rotary magnet and also prevents a discharge circuit being completed for condenser QA after the interrupter contacts m close. During the ensuing make period condenser QA continues to charge. a

The circuit functions in the manner previously described if the second impulse train comprises two or more impulses arid" approximately 140 milli-seconds after the commencementof the break period of the last impulse of the train, the voltage on condenserQA rises tothe flashing point of neon tube whereupon the tube strikes and brings "up relay C. This relay in operating, at its armature cl disconnects the impulsing circuit andopens the locking circuitof relay B, at armature c2 completes a locking circuit for itself via the rotary off-normal contacts NR3, and at armature'c3 opens the holding circuit for relay E which therefore commences to release. During the release time of relay earth is extended over armatures bl, cl and c3 and the lower winding'of the switching relay H to the P wiper and the subsequent operation depends on whether the selected line is free or engaged.

If the selected line is free, wiper I? will encounter battery and relay H therefore operates and at armature hfi completes a lockingcircuit,

for itself, and at armature hi applies full earth to the P wiper to operate the calledsubscribers cut-off relay in known manner. When relay E releases after its slow release period, a -ci'rc uit for ringing the selectedpartysbell is completed as follows: earthed ringing current generator GNR, common lead 13, upper winding of the ring trip relay F, arm'atures el, f2 and 122' to the negative line, the selected partys belland condenser, the positive line and armatures 713 and ]3 to battery via the ringingreturn resistance YC. During'this time ringing tone is returned in a balanced circuit to the calling party by the connection of a'ringin'g tone source'over common lead H and armatures h! and f4 to the middle winding of relay A. When the wanted party answers, relay F operates-and thereupon at armature fl locks over its lower winding in series with the upper winding of relay H, at armatures f2 and 3 trips the ringing and completes the speaking circuit, and at armature f-l opens the ringing tone circuit. Batteryifeed is supplied to the calling subscribervia the windings of relay A and to, the-called subscriber via the windings of relay D which is connected .across the outgoing speaking leads by way of armatures M and k5; Relay D operates over the called subscribers loop and at its armatures di and d2 reverses thebattery connections to give super: vision to the calling side of the connection. I

At the end of the conversation whenthe calling party hangs up, relay A- releases and in turn releases relay B which thereupon brings about the release of relays C,- F, H andD, Atarma: ture b3 earth is removed from theincoming P conductor to bring about the release of the preceding switches. At armature b4 earth is extended over. the operatedofl-normal contacts N2 to energise the release magnet ZM which is connected to battery via suitable delayed alarm equipment connected to common lead 14; the wipers are thereupon restored to normal backwar dlyover the path along which they have been set and the switch is completely released.

If the. called party is busy when his line is seized, wiper, P will encounter earth andlrelay H will fail to operate. Hence on the release of relay E, ,a circuit willbe completed for 'rel'a'y G fromearth over armatures bl, cl and 03, contacts NRI and armature h8. Relay G thereupon at armature gl extends busy tone from common lead It to'the middle winding of relay A from which it is returned to the calling party. .When the calling subscriber hangs up, relays A, B, C and G are released and the switch is restored to normalas before.

,Assuming now that after taking the switch into'use the calling subscriber hangs up before dialling, relay A inreleasing will ,produce the same'eifect as the first break of an impulse train and will energise'the vertical magnet VM, while relay'B will remain locked to earthover armatures bl and cl. The vertical, magnet on energising raises the wipers to the first level, opens its interrupter contacts 'um and brings about the operation of the off-normal springs, so that condenser QA, after" being initially dischargedon release of relay A, commences to charge-on the operation of contacts vm'and N I.; After the predetermined timing period has elapsed," the neon tube I NT flashes and operates relay C which looks to the earthed armature b't'wh'er'eupon the circuit for both the vertical magnet and relay B is disconnected at armature cl. Relay B upon releasing, at its armature b tv opens the ,holding circuit for relay 0 and, atv the same. armature completes a circuit for the release magnet ZM so that the switch'is restored to normal.

Similar remarks apply if the subscriber hangs up. before diallingthe final digit or during the dialling of the first or second digits received by the final selector in which case the speed timing arrangement, on coming into operation, and operating relay C, finds relay A normal, whereupon relay B is immediately, released to initiate the restoration of the switch wipers to normal. Normally, as has been described, the operation of relay C at the end of each timing period will, with relay A operated, initiate either the changeover from the vertical to rotary stepping or the testing of the called, lineaccording as to whether thefirstor secondtrain of impulses received on theswitch is concerned.

Reviewing the impulse speed timing arrangements, it will. thus be seen that provided the impulsesof a train follow one another at a space ing not exceeding the predetermined maximum value, that. is to say, providing the dial speed is not less than seven impulses per-second in the, present instance, the, speed timingdevice will becontin'uously reset by each succeeding impulse until the last impulseof the train has been; received, afterwhich, the timing device comes into operation.. In the .case of a selector switch of the rectangular release type described,

the selector is then caused to out in in every case but subsequently independenceon whether the calling subscriber hashung up or not, the switch is caused to remain connected throughto a succeeding switch or to resume the rotary movement and carry the wipers clear of the banks, after which they restore to their normal position. In the case of a selector switch of theverti'cal and 6. re -y t pe w i jb-e kw d ee; the; bb t @1- normal position of the Av re ay; at the endof the tiniej pr djwillfieterrriine whether the switch will cut'nr or release; In the case of a final selector or other switch' on which more than one digit is 'effectivefatlthe end of the first impulse tilaih the pee tirnin device oncoming in'tofl operationprepares the svvit ch in question forrece'iving the'second digit; V

It will have beennoticed'thatjnfthe arrangef rhe'nt described the speed timing measurements were t'aken from the beginning of each breel; impulse and this 'iS 'preferred i' r the following reason. In e se'e'seie t r s vvitchis seized and the subscriber men halirig's' up his receiver gene but dial1ing,' the only partbf an' impulse vvhich' is received is the break portiemaridaccbrdiri'g'W arelease condition is treated "it'sj the 'first' break mpuls 9 m l e' i ilifi y d ierned. t m n e le a e w t ut-e m ner pulse being jrece' (1, s is evidencethat either the u te.d. 2m 9 1. the pmi lu s j .t ei prop r asf nis d the s 'se st t h an he be, e it d qf w ro e wi thesettingunef the co action in the manner ee d 'qr bed j..

v The iin'n'ulsing ra the erran nii n that represented j by I is bounded on its jhy t'e se -byte 7 impulses p r, ndtdo ifim an? 611 t e. e h r s d bythe linesjMoahd Ma which res'pecti\' ely indream the m tin nim te period requiredlto ens toryoperation a release h qswitphlme net. HTlTW $9 7 paratively large a eas-nave therefore been 'gain'ed which ere; lewith the A; B. C: reiay'tr d arrangenie eyiously femp yed. T i ..p relip e epl not c e for by the c'hnf me lyin o. endit ,6 mak n e er-l mes lf nd'lfi-fl n thew l, a ,ahf c $9 is" limited nineih ts t S. Oiilfi l aw; o im ely ne hji i e s l c imp @Fib nh'etbe' l fidl that the break periods g t he. v tien.

therwise unobtainab vary to such aii ex "The off-normal bre'al; ontact s tonrevide the, 'nitial' enemy I for uicr 'pt nerat -ate energised w h r, H as'takeninto'use; -Another advantage 6; the

inent is t it pen em" ore. qu el'sly her .the d 101L711 pu 'et h s erxiyd than hasbeenpossufle it 'ei t tjnien -p v es a reater xi arei :91. ea. ,e h th g it?. n fie v d n'n w c t me a Sewe sw m a e 6 b b mgaihuntinfe i et vn, iiri nee 'oiitletto asubsequent switch; 'This'feature c1 entree;

beillust piags iiifi g that a selector receives s'tahdard ulseisi atthe rate of ten per second with anre 1-miikei2itittf 2:1; in the exist ing arrang ent the Q relay which is opere in paral 'lel 61f j ries w th the magnet is timed to evee relea e l ger the order of -140 milli-secbnds; and if this relay has the maximum release value 'of 1 mini-seconds, which value it will 'g'enerallyapproach after a numbe tual o'iieiations in practice, it cannot be at the impulse train has finished fmilll-seeqnd s after the end of the last Break impulse Referring to Fig. 3, the last break impulse ere t iri'off two imp ul ses of the chai' j oinrnences at'point Y so that 140 plus 661:6 "equals 20 l5'.6 Infill-seconds will elapse new t e begi ning bf the last im ulse of the train" hefbre thedeci'siQncan' be made. In the nithod; 5e i dihg 't'q' 'the invention, the speed timnrg ofi mences at the b'oint Y representing the pegmeni fer the lest breakii'npulse, and assume thatthefs'vvitchhiagnet ha a maximum o erat time ianfiiiinieedhds, ama that the conq nser ne htupe timing} circuit is set at a value r gqmi liis eeegamy 9; total of 1 40'mil1i-s'ecee gro tn Beginning ofth last break impulse need elapse before the switch can cut in and hunt or relea se The new ihethqdthus in this instance e vese Wine Tire? 69 millif brr the old, we en u h th seizin i iqrl i i lbwr rates Q1; 21' me and d p ee e uw tl fatier rlts' of dialinaitisap rtia ei revs i the W618 range of impulse speeds of from 7-14 impulses per e smd- It is apparentthat thejmproved arrangement is in nqsense limitedtqtthe precise timing values described, The invention moreover is not limited to the exact electricalmetmd of timin described as similar resultscould be obtained for instance by utilising aichange of resistancedue to a heating effect to alter the potential of the grid of a thermionic valve or alternatively a valve might be employed arranged so that it would emit electronspnly afteran interval sufiicient to heat the cathode. Use could also be made of resettable electrQ-mechanical mechanisms for the same purpose: Furthermore the applications of the invention may-include forms of selecting mechanism otherthantheldirect 'step-by-step drive type, and in the caseiofxappiicationto switches of the common motor drive type; the use of electro-mechanicaltiming mechanisms operated from the same drive may'prove'the-more desirable.

"'It will also be understood that though the arrangement described-whereby the timing Starts atr'the beginning of the break period generally effers certain -advantages, the invention also covers 'timin'g'fromany given point in one impulse tothe corresponding-point in the suece'e'd ing im1i1se. This jhay beer mere imboitan'ee'if the impulses not simple ifiake and Breaks but of a mere 'cemeii'cetee type, for instance re ers ls m permiasee fr diiferent frequencies of al'te ating cl'lrriit or combihatiohs ofdi iect and a1ternati'ng' curr nt. I v invention" 'eeeeminry sl et/nee an impj ygii feftfioubr iiiinfils response 'tvhieh 'o' erates on ne'irel brin'lpl'es'inthat iniimise ratio'is ignored and each impulse -is dealt with age; wholeplt will be appreciated that this method of'attackingv the problem; differs fundamentally from impulse correction schemeswhichaimat re-adjusting the ratio of received impulseswhich have suffered distortion. q

.What 1W8 claim as new and desire to secureiby Letters Patent is: U 1. In yacsignaling system. wherein; different trains of impulsesare transmitted over a .signali-i ing circuit at different times, wherein each of said trainscomprises a variable number of spaced apart impulses, wherein all impulses in the same train are of a uniform" duration and successive ones thereof are spaced apart by a uniform interval, and wherein the duration and spacing of impulses'in the different train are different, timing equipment, means for receiving said impulses and, responsive'to the beginning of the first impulse of eachtrain, causing said timing equipment to begin a. timing operation, said means responsive to the beginning of each succeeding impulse of the train to cause'said timing equipment to halt the timing operation 'prewously started and to b e g in another timing operation,

whereby thetiming operation initiated by the beginning of eachimpulseexcept the last impulse in'leach'train is halted responsive to the beginning of the next impulse in the same train, .and means controlled by said timing equipment for halting the timing operation'initiated by the last impulsein each train an arbitrary interval of time after the initiationof such impulse;

2. In a signaling system wherein different trains of impulses are transmitted'over a" signaling circuit at different times, wherein each of saidtrains comprises avariable number of spaced apart impulses, wherein all impulses in thesame train'are of a uniform duration and successive ones thereof are spaced apart by .a uniform interval, and whereinthe duration and spacing of impulses in'the different trains are different, timingequipment, means for receiving said impulses and, responsive to the beginning of the first impulse of. each train, causing said timing equipment tobegin a timing operation, said means responsive to the beginning of each succeeding impulse of the train to cause said timing equipment to halt the timing operation previously started and to begin another timing operation, whereby the timing operation initiated by the beginning ofeach impulse continues until halted by the beginning of the next'impulse, if one follows, regardless of the ratio of the duration of the impulse bywhich such timing operation was started to the interval between the ending of that impulse andthe beginning of said next impulse, and means operated by said timing equipment if any timing operation is not halted within a predetermined interval of time after it is initiated.

' 3. In "a signaling system wherein different trains of impulses are transmitted over a signaling circuit at different times, wherein each of said trains comprises a variable number of spaced apart impulses,"wherein all impulses in the same train are of a uniform duration and successive ones thereof are spaced. apart by a uniform interval, and wherein the duration and spacing of impulses indifferent trains are different, an impulse receiving device associated with said signaling circuit, said device operated in a certain way responsive to the beginning of each impulse and perated in adiiferent way responsive to the end of each impulse, timing equipment controlled bythe operations of said first devicedn one of said ways but .not inthe other of said ways, said timing equipment effective,

whenever one of said impulse trains is received,

to initiate a timing operation responsive to the first operation'of said device in said'one way, said timing equipment then effective responsive to each succeeding operation of said device in said one way'to halt the timing operation which was initiated by the preceding operation of said device in said one. way and to initiate another timing operation, and means operated by said timing equipment if any timing operation is not halted within a predetermined interval of time after it is initiated.

4. Ina signaling system wherein a train of impulses is transmitted over a signaling circuit, wherein said train comprises a variable number of-gspaced-apart impulses and wherein all impulsesinsaid train arev of a uniform duration and successiveonesthereof are spaced'apart by a uniform interval, an impulse receiving device associated with said signaling circuit, said device operated ina certain way responsive to the beginningof, each impulse and operated in a different way responsive to the end of each impulse,

timingequipment controlled by said device to initiate a timing operation responsive to each operation of said device in one of said ways, said timing equipment also controlled by. said device responsive toeac'hsucceeding operation of said,

device in said one way to halt the timing operation which was started responsive tothe next preceding operation of said device in said one way. 7

. 5., In a signaling system, timing equipment, a circuit over which a variable number of spaced apart impulses are transmitted, saidimpulses all beingofauniform duration and successive ones of saidimpulses being spaced apartbya uniform interval, an impulse receiving device associated with said circuit, said device operated a certain,

way responsive to the beginning of each impulse and, operated a different way responsive to the end of each impulse, means controlled by each operation of said device in one of said ways'to cause said timing equipment to start a timing operation, said means also controlled by each operation of said device in said one way to cause said timing equipment to halt any timing operation'which may then be in progress as the result of a previous operation of said device in said one way, and another device operated by said timing equipment if any timing operationis not halted within a predetermined interval of time after it is initiated, Q

6. In combination, timing equipment, a device having a normalcondition; means for operating said device a variablenumber of times in succession and for restoring said device to normal aftereach said operation, the successive ones of said'o'perations occurring 'at regularly spaced intervals, 'means controlled by the first such operation of said device for causingsaid timing equipment to start a timing operation and controlled-by eacl'i succeeding operation of said device,- if any, for causingsaid equipmentto stop the previous timingoperation and start' a new timing operation, and means operated bysaicl timing equipment if any one of said timing,

operations-is not stopped Within a predetermined time'a-fte'r it isstarted;

7. A combination as insa'id timingequipment is wholly static and performs 7 said timing operation without, any physical movement. J :r r y claimed in claim 6, where- "8. In a signaling-system wfi rem 'awerisme number "0': spaced apart iiilp'uls'es are transmitted over a signaling ciiuitfah i-m'piilse iecivihg'devi'c' associated with "said "circuit, sai'a aeviee operated a certain wayressonsive f'to the 'bjginning of each iinpulseand operated aHiflfernt way *r' "pe sive" to the one of each impulses s'ecohddevice; means controlled by tlie ii'fierations of said first device ihoh of {said I Sis but norm theotlrir for operating said second 'd'e'-' vice only when an operation of said first device in s'aidone way not'iollowed by another ope "a tioi'i thefeo'f-in' said 'ciie'wa within a predetermined interval of tifh; and ihans unaer tne joint control of said two device's'op'eratedhiffi'eiitlyde ending-neon newa in which said first device I rs operated at the time said "second device operates;

9 In a signaling syster'r'iwherein"avariable nurse-er of's'pac'ed' apart impulses are transmitted over a signaling circuit; ah-impulse receiving device associatd'vvith' 's'aid cirouit,"'said 'deiiice operated a certain way fespon's'ive'to the" begin second device, and means controlled ay the oper at'ions of said-first device iflone'oisaia'vmys out not in the other for o'per ng sa'id second? be only when anop'er ation o f said fi'is't" devi in said one way is not'rbneweq by astute" operation thereof in said one way within a redtrfiiiaea interval or time. I I 1 i0. In a signaling system :wherein a'-"""""abl'e number of spaced apart impulses areuahsniitta over a signaling circuit, an impulse receiving device associated with said c'i rcuit,'-s'aid"device operated a certain way responsive to "ginning of each impulse and operated a different way responsive to the end of achg mpulsea second device, time delay 'n'ieah's "conditioned by each operation of said first device in foneof s'ai'd ways to Operate said's eco ird device were predetermihedinterval of time, and means responsiv'e only to another operation of s'ai'dfi'rst device in said one way within sai interval-or time rat preventing the operation "or said seconddevice by "said time delay means. V V

:11. A system as claimed iii claim io 'waerm said time delay mean includes a con enser, meahs'for varying tfi'etnar'ge pn'saie condo progressively, and means for determining hen the charge on said condenser reaches remain -12' In a signaling 'systin"wherein' awe-H me number of spaoed apart impulses are transmitted over a signaling circuit, an impulse receiv ng device associated with said circuit, said device operated a certain way responsive "to tho paginning of each impulse and operated acirrereht way responsive to the end of eaoh impose, 'a condenser, a charging circuitjand a discharging circuit or said condenser, and means eoa'tjrbnea by 'eachoperation of said device-in one of ways for first rendering said discharging circuit effective to discharge said condenser-andfthen, independ-ently 'of the operation of said device in the other ofrsaid-ways, substantia-lly at once rendering said charging circuit efiective to charge said condenser.

13. In asigna-ling system wherein-a variable number of spaced apart impulsesare transmitted over asignaling circuit, an impulse receiving device asso'ciated'with said circuit, said device operated a "certainway'responsive to the beginning of each impulse and operated :a difierent way coaster responsive to the end cream impulse, a can denser," meanscoritrolld by the operations of said device in one "or saiii ways but'not in the other, "said 'means" effective responsive to each operation of said device in saidone wayflrst'to bring said condenser to apredetefmined state orchar'ge and then to 'changeits state of charge at a predetermined rate.

- "14; In a signaling system, a circuit over which impulse trains are transmitted, a condenseig'impuls'e receiving means effective in response to ach'impulse or a train first to-bring'said condenser to a pre'determinedstate of charge and then to change its state of charge at a predetermined -rate-, whereby-said condenser -is not changed-more than'a certain amount 'from said predetermined -state of charge 'so long as the successive ones of said impulses are received with certain frequency and means operated under control of said condenser whenever it is changed more than said certain amount from said predetermined state of charge. I

' 15 In asignalifig system a circuit over which imp lsejtrain's are transmitted, a, condenser, recfei'vm'g' mean s' erreaive in'r'espo'nse'to each impuls'e' fof a train first to discharge said condenser and thento charge saidfcohdenserat aprdteriniii'ed rate th'r'oi'fglioiiiftfiebalafnce of steamulse, whereby, so mag "as "said impulses are received with certain frequency, the charge on said condenser 'ri'ever r 'che's apredeterhiined value, and an 'electr'onicval've connected to said condenser and rendered operative responsive only to the charge thereon reaching said predeter- '16. i ombination, a devi'ce, means for causing sai'd device alternatlyto assume two different' conditions, a condenser, frne'ans operat whenever saiddevicelis changed from one or said conditions to th'e'other for first bringing said condenser to a p1e'd'et'riiiihd State of charge and-then changing its state of charge at a predetermined rate until "said device again is changed from said'ohe condition to 'said other conditionjwhereby, so long; as said device is ch'a d from said on'econditioi'i to said other co dition with certain frequency, said condenser is'ii'ot changed more than a certain amountfro'in saidp'ieii'termihed state of charge, and an clot trbhlc 'valve "connected to said condenser and rendered operative responsive only to the charge thereon changing more than said certain amount 's'aid predtrmi'fiedstate of charge.

17. In a signaling system wherein thehow or currl'itih a signaling" circuit is t'ra'frisitoiily interi f i 'ted at iega ariiiterv'als for a certain number of times, a device, and means controlled by each said interruption, but'iiidependntly of the length of that interruption, fo'r opefating 'Said device onlylwh'en'one of 'samihterruptiohs is not r01- lowed by another "within an arbitrarily flied period which is slightly longer than said intervals.

, 18. In a signaling system, a device, a signaling circuit over which trains of -impu1s e sare transmitted; each said impulse being divided into two complementary periods having a certain ratio to each other; and means controlled bythe speed of successive impulses but independently ofthe ratio of the periods of anyindiv-idual impulse to operate'said device responsive only to the last impulse of;a train. v

'192'11? a signaling system, timing equipment, means for generating an electrical wave-having a repetitive pattern, a device controlled by said wavetooperate ina particular way at the same point in each repetition of said pattern, and means controlled by one operation of said device in said particular way to initiate the operation of said timing equipment and by a subsequent operation of said device in said particular way to halt the said previous operation of said timing equipment and initiate a fresh operation of said timing equipment.

20. In a signaling system, timing equipment, means for generating an electrical wave having a repetitive pattern, a device controlled by said wave to operate in a particular way at the same point in each repetition of said pattern, means controlled by one operation of said device in said particular way to initiate the operation of said timing equipment, said last means controlled by each subsequent operation of said device in said particular way to halt the operation of said timing equipment which was initiated by the immediately preceding operation of said device and to initiate a fresh operation of said timing equipment, and a second device controlled by said timing equipment to operate if any operation of said timing equipment is not halted within a predetermined time after it is initiated.

21. In a signaling system wherein a signal having a repetitive pattern is transmitted over a signaling circuit, a device, time delay means under the control of said signal and conditioned by the same point in each repetition of said signal pattern to operate said device after a predetermined interval of time, and means effective whenever said time delay means has been conditioned by an occurrence of said point in one repetition of said signal pattern for preventing said time delay means from operating said device only if the same point in the next repetition of said signal pattern occurs within said predetermined interval.

22. In a signaling system wherein a mechanism is moved step-by-step under control of an impulse train, means for receiving the impulses of said train and operating said mechanism one step for each received impulse, timing equipment controlled by said step-by-step mechanism to initiate a timing operation responsive to each step taken by said mechanism, and means operated by said timing equipment whenever said first means fails to receive a further impulse within a predetermined interval of time after the initiation of said timing operation. i

23. In a signaling system wherein a mechanism,

is moved step-by-step under control of a train of spaced apart impulses, a device for receiving said impulses and causing said mechanism to step in accordance therewith, said device operated a certain way responsive to the beginning of each impulse and operated a difierent way responsive to the end of each impulse, a second device, time delay means conditioned by each operation of said first device in one of said ways to operate said second device after a predetermined interval of time, and means responsive only to another operation of said first device in said one way within said interval of time for preventing the operation of said second device by said time delay means.

24. A system as claimed in claim 23, wherein said time delay means includes a condenser, means for varying the charge on said condenser progressively, and means for determining when the charge on said condenser reaches acertain value.

' 25. A system as claimed in claim 23, wherein said time delay means includes a condenser, means for varying the charge on said condenser progressively, and an electronic valve connected to said condenser and rendered operative responsive only to the charge on said condenser reaching a certain value.

26. In a signaling system wherein a mechanism is moved step-by-step under control of a train of spaced apart impulses, a device for receiving said impulses and causing said mechanism to step in accordance therewith, said device operated a certain way responsive to the beginning of each impulse and operated a different way responsive to the end of each impulse, a second device, means controlled by the operations of said first device in one of said ways but not in the other for operating said second device only when an operation of said first device in said one way is not followed by another operation thereof in said one way within a predetermined interval of time, certain equipment controlled by said second device upon operation if, at the time of such operation, said first device is operated in said certain way, and other equipment controlled by said second device upon operation if, at the time of such operation, said first device is operated in said diiferent way.

27. In an automatic switch, a line over which spaced-apart impulses are received, a line relay 7 next impulse in said train, if one follows, wherev, by, so long as said impulses are received with a certain frequency, the charge on said condenser never reaches a predetermined value, an electronic valve connected to said condenser and rendered operative responsive only to the charge thereon reaching said predetermined value, and

a relay in the output of said valve controlled by v the operation of said valve. 

